The invention relates generally to two-dimensional transducer arrays. In particular, the invention relates to techniques for addressing individual transducer elements within a two-dimensional transducer array.
A medical ultrasound imaging system forms an image by transmitting an acoustic wave into a subject and receiving and processing the reflected acoustic waves. Typically, a plurality of ultrasonic transducers both send the transmitted wave and receive the reflected waves. Such scanning comprises a series of measurements in which the ultrasonic wave is transmitted, the system switches to receive mode after a short time interval, and the reflected ultrasonic wave is received, beamformed, and processed for display.
The transducer elements are typically driven individually by an input voltage waveform. By implementing time delays and amplitude differences between the input waveforms, the individual transducer elements can be controlled to produce ultrasonic waves that combine to form a net ultrasonic wave that travels along a preferred vector direction and is focused in a selected area of the subject. Similarly, the reflected waves received by the transducers may be mathematically processed so that the net signal is indicative of the sound wave reflected from a single focal zone in the object. As with the transmission mode, this focused reception of the ultrasonic energy is achieved by imparting various time delays and gains to the signals received from the transducer elements and summing the resulting waveforms.
The quality or resolution of the image formed by the ultrasound imaging system is partly a function of the number of transducers in the array. Accordingly, to achieve high image quality, a large number of transducer elements is desirable. Furthermore, each transducer in the transducer array is coupled to the transmit and receive circuitry via an individual electrical connection. The technical difficulty and expense of fabricating a large number of electrical connections may limit the number of transducers that may be included in a typical transducer array. It may be advantageous, therefore, to provide improved techniques for addressing the transducers in a large two-dimensional transducer array.